schmidt



ENGINE.

:f -mo Moden) P-atentedApr. 30, 1895.

ZZ/ 57W @da ad (No Mjodel.) 2 Sheets--Sheet 2.

' W. I'. SCHMIDT.

ENGINE No. 538,433. PatentedApr. so, 1895.

NITED STATES PATENT union.

VILLIAM F. SCHMIDT, OF ST. LOUIS, MISSOURI, ASSIGNOR TO PIERRE CHOUTEAU,OF SAME PLACE.

ENGINE.

SPECIFICATION forming partof Letters Patent N o. 538,433, dated April30, 1 895.

Application filed' June 15, 1894. Serial No. 514,652. (No model.)

To all whom it may concern:

Be it known that I,-.WILLIAM F. SCHMIDT, a citizen of lthe UnitedStates, residing in the city of St. Louis, State of Missouri, haveinvented a certain new and useful Improvement in Engines, of which thefollowing is a full, clear, and exact description, reference being hadto the accompanying drawings, forming part of this speciiication,wherein- Figure l is a longitudinal section showing the piston in acentral or lap position. Fig. 2 is a similar view showing the piston onits upstroke. Fig. 3 is a similar view showing the piston on itsdownstroke. Fig. 4 is a longitudinal section of the cylinder, showingthe arrangement of the exhaust-ports; Fig. 5 is a top plan view of thesame. longitudinal sectional view of another form of cylinder, showing aportion of the piston in its extreme low position. Fig. 7 is acrosssectional view taken on line 7 7, Fig. 6. Fig. 8 is a detailed viewof' the cylinder-lining shown in Fig. 6, and Fig. 9 is a detail View ofthe piston.

My invention relates to a new and useful improvement in engines, and isillustrated in y the drawings as being applied for use in connectionwith what is known as a dneumatic hand-tool, or a tool in which a chiselis caused to be vibrated by the impact of a piston; but it is obviousthat the-principle of operation which I have here illustrated couldbeadvantageously applied tol other forms of engines, and to engines usedfor other purposes.

Heretof'ore, so far as I am aware, all engines ofthe characterillustrated, and, in fact, en-

gines of all descriptions, have included as es-V sential elements oftheir construction ar cylinder, a piston, and a controlling ordistributing valve, which controls the exhaust and admission of themotive fluid above and below the piston. This controlling valve, inhowever diverse form, is found in all 'constructions where a piston iscaused to be reciprocated by the admission and exhaust of motive fluidabove and below the piston. In my present invention, I dispense entirelywith this controlling or distributing valve, and by so arranging theports in the cylinder the piston itself is caused to control theadmission ing the motive fluid from its source of supply.

The inlet port 1 opens into the bore of the cylinder at about itsmiddle, and is opened or closed by the upper or lower head of thepistom-when said piston is in either of its extreme positions. Thepiston Bis formed with a recurved portion `or annulus about its middle,into which the inlet port l normally opens during the operation of themachine.

2 and 3 are connecting ports opening from points above and below themiddle portion of the bore to the upper and lower ends ot' the bore.

and 6 are exhaust openings connected to a common exhaust 7, leading tothe exterior, or said exhausts may lead directly to the exterior, as isobvious. n

On the lower end of the piston, a stem E is provided, which stemoperates in an opening formed in the lower end of the cylinder and upontool-shank C. The extreme lower end of this stem entirely fills itsopening, while the upper portion of the stem is cut away at its sides,so that the motive fluid can escape through the stem opening and toolshank opening for purposes hereinafter described.

The operation of the tool constructed as above is as follows:` Assumingthat motive fluid is admitted through port clinto the inlet port l, andthat the position of the piston is as shown in Fig. l. In this positionof the piston, the motive fluid can go no farther than the space formedby the annulns. lAssuming now that the engine is tilted slightly, so asto cause the piston to uncover the lower opening of port 2. Thiswillestablish communication between the inlet port and the space abovethe piston, and cause the piston to descend with force. On thedownward.- movement of IOO the piston, its upper head will close thelower opening of port 2 and its lower head will open the upper openingof port 3, thus cutting o communication between the inlet port and thespace above the piston, and opening conimunication between the inletport and the space below the piston. At the same time, the upper headwill open port 5 so `as to exhaust the air from above the piston-port 6in. the downward position of the piston being closed. The piston is nowcaused to ascend, which will close exhaust port 5, close the upperopening of port 3, open exhaust port 6, and then open the lower openingof port 2, in the order named, the reverse being the case when thepiston is descending; and so this cycle of operations is continued.

To control the speed of the tool, I have connected theexhaust ports to acommon leadout, which lead-out or mouth, when choked or closed,and notpermitting the full amount of air to exhaust, will, consequently,decrease the number of strokes of the piston, but which when permittedto exhaust fully will allow the iston to run at its maximum speed.

It will be noted that by the arrangement of the several ports, if thepiston were permitted to make an extreme stroke at each operation, itwould be cushioned at both ends, as the stem E does not pass beyond theshoulder formed in the cylinder to arrest the inward movement of thetool-shank until after the upper piston head has closed the inlet-portl.The advantage of this is, that very often it is desirable to use thetool from time to time without heilig compelled to cut off the supply ofmotive duid, nor permit the tool to run without doing any work,thuswasting the motive iiuid. To stop the reciprocation of the piston, and,at the same time, have it ready for instantaneous operation, I choke theexhaust until the piston sinks to its lowest position,when the confinedair beneath the pis ton will escape through the stem and shank openings,and the upper head of the piston will close the inlet port l. To startthe tool when the motive duid is thus turned full on, and the tool hasbeen dead, it is only necessary to elevate the forward end until theupper head of the piston passes above the inlet port, when it will startimmediately to reciprecate.

I have shown in Figs. l to 4 a bored cylinder, made of one piece, but itmay be found desirable to make the cylinder of two pieces,

as shown in Figs. 6 to 8, and in which a lining Gr is inserted in thebore, which lining is formed with suitable port openings to theinterior, the outer periphery of the lining being led or otherwisereduced to form the connecting port. in Fig. 7, I have shown this liningin position in this cylinder, and have, also, illustrated a blind-port8, which is of practically no use save for purpose of equallydistributing the metal around the cylinder.

I-Iaving thus described my invention, what I claim, and desire to secureby Letters Patent, is-

l. In an engine, the combination with a cylinder which is formed with aninlet port opening thereinto about midway its length, ports 2 and 3which lead from each side ot the inlet port to the ends of the cylinder,and exhaust ports which lead from the cylinder at points between theopenings of ports 2 and 3 into the cylinder respectively, of a twoheadedpiston mounted in the cylinder which co-operates with said ports, anda-stem on the piston which projects through an opening in the forwardend ol' the cylinder, said stem being so formed that when the piston isin an extreme forward position, it permits the motive fluid in front ofthe piston to exhaust so that one of the heads will align with the inletport to close the same; substantially as described.

2. In an engine, the combination with acylinder provided with suitableinlet and exhaust ports, ot' a piston operating therein,a stem on thepiston which projects through the forward end of the cylinder, said stembeing so formed that when the piston is in an extreme forward positionit exhausts the motive fluid in front of the piston and permits thepiston to close the inlet port, substantially' as described.

3. In an engine, the combination with acylinder, of a piston mountedtherein, and a stem on the piston which projects through an opening inthe forward end of the cylinder, saidstem being formed with reducedsides and a cylindrical outer portion, substantially as described. y

In testimony whereof I hereunto affix my signature, in presence of twowitnesses, this 9th day of June, 1894.

WILLIAM F. SCHMlDT.

Witnesses:

F. R; CORNWALL, HUGH K. WAGNER.

In the cross-section shown j IOO

